How much time effort do you have to put in? Can i obtain it without using goldd??

You can get it easily without gold. Just do your best in NW and use your winning toward uncannies. 1 supply stash token = 5 uncannies.
So 50 supply stash tokens = all you need to make ine hh99 piece into second cast.

Do your best to farm hh99 to make second cast, and if you're too incompetent to farm then just sell the cannies until you can buy the materials.

Now once you've used NW to make all your 2nd cast NV gear, use mirages and tisha to get it to around +5 then start doing full WS for your g16 molds. The end.

lets say it like that: Yes it is farm able, BUT you need a decend gear to solo a pavilion. So either you got a well geared char already to do it with that char or you need to spend some money on Morei G15 Gear to have sth to start with or Nirvana..(Nirvana weapon will be too weak for some classes, others even manage with R8)...

For the idea of merchanting/buying it its comparable cheap. Depends a bit on the server, but is still not out of reach..

All in all its a cheaper version than R9, but in the end you usually don't want the second best equip, so you will start saving for R9 recast any way

Lets say you are at the point of being lvl 100 and having TT90 gears since that is where you mostly end up after doing a normal game of leveling and slowly upgrading your gear as you level.

First you need TT99 gold gear. If you want to farm this with your TT90 gears, you are gonna have a very tough time. You cant solo it, so youll have to squad. You will always be the weak guy in the squad which the others may accept as a member only if you are a good support character: cleric, veno or barb. Else, little chance of even being in a squad. If you do manage to get into a squad, your gonna be doing for example 2 months of doing TT3-x runs. That will get you most of the base mats you need, but not the gold ones because the squad will sell those, or randomly share those, or give them to the main overpowered guy who does most of the work. So you still need to buy about 10 TTgold mats at an average of 5m coins or so each. 50m total, probably a little more.

The other TT mats you have farmed for your needs are worth another 50m. Maybe you have gotten some extra that you dont need and could sell to get the money for the gold mats.

Then comes the upgrading to G15. you need some 1000 or so uncannies. Value currently varies per server between 10m and 50m for the 1000. Still dropping till it will be 10m on all servers. Besides that you need some 250 raps for another 10m. So this was the easy part. You can get them yourself from NWs, even if your a noob, it will just be slower.

Then to get to G16, you need to farm for molds that are untradable. This is a matter of luck since they are random drops. It could take days, weeks or months.

Getting the money for the TT gold mats is probably the main issue. You can do this by farming extra non gold mats and sell those, by doing well enough in NW that you get more supply tokens than you need yourself, or by merchanting.